Mold for battery grids



Oct. 22, 1940. I K OOD 2,218,612

ifiammfimmfim BB nmunmunmunununuuunununununununwmunun Illll Illll l I II I [MI W w 5a. ATTORNEYS LZ 1940- H8. LOCKWOOD" now FOR BATTERY earns Filed Aug. 4, 1938 3 Sheets-Sheet 2 mm gnn 180%717'02 -flneer J Zacmvoao Patented a. 22, 1940 MOLD FOR BATTERY GRIDS Harry B. Lockwood, Cleveland Heights, Ohio, as-

signor to Willard Storage Battery Company, Cleveland, Ohio, a corporation of West'Virginia Application August 4, 1938, Serial No. 223,069

1 Claim.

This invention relates to improvements in molds for battery grids and has reference par-- ticularly to a provision in the construction of a mold for storage battery grids which facilitates the escape of air from the mold as the metalis poured into it, and which by permitting rapid filling of the mold makes feasible the useof lead alloy metal with a smaller proportion of antimony and at a lower pouring temperature-than has been possible heretofore.

One of the objects of the invention therefore is the provision of a mold of the character stated which promotes rapid filling of the cavity by the molten metal.

Another object is the provision of a moldv which will permit the use of lower cost metal.

Another object is the provision of a mold which.

will permit the pouring of a given non-ferrous metal at lower temperature than has been pos sible heretofore. v Other objects and features of novelty will appear as Ipr'oceed with the description of that embodiment of the invention which, for the purposes of the present application, I have llustrated in the accompanying drawings, in which Fig. 1 is a fragmental elevational view of one end of a mold for storage battery grids.

Fig. 2 is a fragmental elevational view on a larger scale of the inner surface of one of the mold plates or halves.

Fig, 3 is a transverse sectional view taken substantially on the line 3-3 of Fig. 1 on a considerably larger scale. I

Figs. 4 and 5 are elevational views of the inner surfaces looking in the direction of the arrows 4-4 and 5-5 of Fig. 1.

Fig. 6 is a fragmental view similar to Fig. '3 but on a still larger scale.

Fig. 7 is a vertical sectional view of the two mold plates, the view corresponding to the line 1-1 of Fig. 2.

Fig. ,8 is a fragmental view on a still larger scale of a portion of the section illustrated in F18. 7.

In Figs. 1 and 2 mold plates or halves are indicated'at l0 and II, with their backing plates l2 and I3 respectively. Means for locking the mold parts together is indicated at M and I5, and a chute for discharging the castings after the mold has been opened is indicated at IS.

The drawings show a mold for casting two grids simultaneously, but it should be understood that this is for illustrative purposes only as the invention may be applied to molds for casting 88 single grids or for casting a plurality of grids c1. zzss) i v greater than two. When the mold halves are brought together close contact is effected between the accurately finished plane surfaces surrounding the mold cavity, these surfaces comprising parts l1, l8 and IS in mold plate l0, and l1, l8 and IS in mold plate ll. Throughout the space in which the body of the grid is to be cast there are of course small plane surfaces 9 of approximately rectangular form which correspond with the spaces between the bars of the 10 grid. There are also slender plane surfaces 20 and 2| in plate I0, and 20' and 2| in plate II, which are for the purpose of providing breakage lines by means of which the two grids may be readily broken apart after the casting is 15 formed.

The cavities in the two mold plates are flared at the top as indicated at 22 and 22 to provide a trough into which the molten metal may be poured. When the metal enters the mold m proper it must descend between small spaced vertical barriers 23 and 24, 24' which serve to evenly distribute the metal across the entire width of the mold.

In accordance with the preferred form of my 28 invention the mold plate H is formed in the usual way to include approximately one-half of the mold cavity. The mold plate It! includes the other half of the cavity, but it departs from the usual construction in that an undercut25 is ma- .0 chined or .ground into its surface, this undercut extending throughout nearly the entire area of the cavityfor each individual grid. The outer edges of the undercut for each grid are indicated at 2B in Figs. 2 and 4. -In forming this undercut 86 the inner surface of the mold plate is machined or ground down to a small extent only, that is to a depth of the order of one and one-half thousandths of an inch. 1

Vent holes 21 are provided in one or the other 49 or both of the plates I0 and H, but preferably in the plate H exclusively, these vent holes being connected with vent openings 28 in the backing plate l3.

The making of castings by the use of my im- 45 proved mold involves the same procedure as is, followed in the use of conventional molds now in common use, that is to say after the mold surfaces have been cleaned they are coated with a heat insulating mold coating applied by a spray 5o gun and indicated at 29 in the drawings. Then a steel scraper is used to remove all of the coating on the plane or meeting surfaces of the two plates, the coating remaining in the cavities of both plates and also in the undercut parts of plate "I. When the two mold plates are put together a very thin relief 30 is left between the coating 29 .on the undercut portions and the scraped plane surfaces of the mold plate H, the previously stated depth of the undercut, that is one and one-half thousandths of an inch approximately, being such as to leave the desired relief after the undercut surface is coated. -This thin relief is sufficient to permit air to escape to the vent holes 21, but is not sufiicient to permit the flow of molten metal therethrough. In fact the metal is chilled andsolidifies immediately upon striking the relief. The air displaced by the molten metal flowing down through the mold interstices is easily dispelled however through this relief and the flow of the metal is therefore greatly facilitated. Because of this more rapid flow a metal of lower antimony content may be used, or the same metal may be used at a somewhat lower temperature. By way of example it may be noted that whereas a common practice in the casting of grids for storage batteries prior to the present invention was town a lead alloy containing 12% antimony at 1100 F., a 9%% antimony alloy may be poured in my improved mold at from.920 F. to 1050 F.

Although I prefer to undercut mold plate ll only, it is within the spirit of the invention to form the undercut partly in one plate and partly in the other, in which event the relief would be between two coated surfaces instead of between a scraped plane surface and a'coated surface. tion to undercut'plate ll exclusively ratherthan plate III, in which event the undercut and the.

vent holes 21 would all be in the same plate.

Variations from the described structure may be employed. Accordingly I desire it to be understood that the scope of the invention is to be regarded as defined exclusively by the appended claim rather than by the foregoing description or the accompanying illustrations.

Having thus described my invention, I claim:

In a mold for casting storage battery grids, a pair of mold plates having matching mold cavities in their adjacent relatively plane faces, one of said plates being undercut from its plane meeting face throughout a large part of its surface, the cavities of said mold and said undercut surface being coated with a heat insulating mold coating, the depth of the undercut being uniform and such that when so coated a relief will be formed between the mold plates intermediate said cavities small enough to prevent molten metal from entering, and one of said mold plates having vent passages connecting with said relief.

HARRY B. LOCKWOOD.

It is also within the spirit of the inven- 

